Date: Thu, 5 Oct 2017 08:25:20 -0700 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: Konstantin Belousov <kostikbel@gmail.com> Cc: linimon@lonesome.com, Don Lewis <truckman@FreeBSD.org>, list1@gjunka.com, freebsd-ports@freebsd.org Subject: Re: portmaster, portupgrade, etc Message-ID: <20171005152520.GA96545@troutmask.apl.washington.edu> In-Reply-To: <20171005145941.GL95911@kib.kiev.ua> References: <20171004232819.GA86102@troutmask.apl.washington.edu> <201710050027.v950RBFT047711@gw.catspoiler.org> <20171005083558.GD95911@kib.kiev.ua> <20171005145116.GA96180@troutmask.apl.washington.edu> <20171005145941.GL95911@kib.kiev.ua>
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On Thu, Oct 05, 2017 at 05:59:41PM +0300, Konstantin Belousov wrote: > On Thu, Oct 05, 2017 at 07:51:16AM -0700, Steve Kargl wrote: > > On Thu, Oct 05, 2017 at 11:35:58AM +0300, Konstantin Belousov wrote: > > > On Wed, Oct 04, 2017 at 05:27:11PM -0700, Don Lewis wrote: > > > > > The system in question is my last i686 laptop, which I > > > > > use for libm development and testing. Once I cannot use > > > > > that laptop (whether hardware failure or inability to > > > > > update the installed ports), I'll stop worrying about a > > > > > functional libm on 32-bit hardware. > > > > > > > > As an aside, this sort of thing could be done in an i386 VM or maybe an > > > > i386 jail on amd64 hardware. > > > > > > You do not need even a jail for this. Base cc -m32 works on amd64 for > > > long time, and 32bit binaries can be executed from host environment, > > > assuming all third-party libs are provided somewhere in the 32bit > > > variant. > > > > > > The environment with regard to the hardware configuration should be > > > identical to modern i386-arch machine with SSE2. Incompatibilities are > > > considered as bugs and are usually fixed fast when reported. > > > > Does this required WITH_LIB32=yes in src.conf? > Yes, but this is the default. > > > > > More concerning is that the FPU on i686 is set-up in npx to > > use 53-bit precision instead of 64-bit. See x86/fpu.h where > > there is a large comment and the settings > > > > #define __INITIAL_FPUCW__ 0x037F > > #define __INITIAL_FPUCW_I386__ 0x127F > > #define __INITIAL_NPXCW__ __INITIAL_FPUCW_I386__ > > > > Does cc -m32 on amd64 cause the amd64 fpu to act (exactly?) like > > and i387? > It is not cc -m32. > > Kernel sets up x87 FPU differently for 64 and 32bit processes. See > ia32_setregs() where pcb is adjusted for 32bit, and r189423. Yes, I know the kernel sets up npx on i686. If one is testing libm changes or new code for libm, then cc -m32 will be insufficient in testing the behavior one might get from i387 in 53-bit mode as oppose to 64-bit. This is the reason the macro LD80C exists in math_private.h. Which brings me back to my i686 laptop with limited resources. If portmgr makes it impractical/impossible to easily install ports without a sledge hammer, then testing possible future patches to libm will simply skip i686 class hardware. -- Steve
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